Method of making zinc roll anode for primary cells



June 17, 1947. F. D. WILLIAMS, JR'

METHOD OF MAKING ZINC ROLL ANODE FOR PRIMARY CELLS Filed Dee. 1o, 1945 Il .an 1 g L c -L M m wv d a, 11 Y. .T g m d IIIIIIL 1./ v, :IIH W A/// /f 5 M l lill!!! llllfllll IIlIIIIIIIIII/Il; It

IN VEN TOR.

ed Milla/#5,12 ay l v @Wem Patented Jun. i7, 1947 2,422,606

UNITED STATES PATENT oFFicE METHOD F MAKING ZINC ROLL ANODE FOR PRMARY CELLS Fred D. Williams, Jr., New Rochelle, N. Y., as-

siznor to Samuel Ruben, New Rochelle, N. Y.

Application December .1.0, 1943. Serial No. 513,818

This invention relates to primary electric cells, their construction and manufacture.

An object is to improve primary cells and methods of making them.

Other objects of th'e invention will be apparent from the description and claims.

In the drawing:

Figure 1 is a perspective view showing a step in the manufacture of a primary cell electrode;

1i claims. (011364130) ity or alkali resistance so that the alkali treatment of the pulp may not be required. v

A plastic sleeve or cylinder I2 (Figures 2 and 3) formed of a suitable plastic such as rubber hylFigure 2 shows a method of amalgamating the 10 l However, if mercury is applied before rolling the electrode; zinc becomes brittle and rolling is made diill- Figure 3 is a longitudinal section through e. cult or impossible. Figure 2 shows a process of completed cell; and/ amalgamation and impregnation which avoids Figure 4 is a sectional view of a modied cell. these difficulties. A number of the anode-spacer The present invention contemplates methods assemblies 9 are placed in a flat bottom dish I4 of making a cell and ,the anode structure therewith the zinc end up. The cell electrolyte I5 is of and a process for amalgamating the anode for poured into the dishl slowly allowing the electhe cell. trolyte to be drawn up into the rolls by capil- In its preferred embodiment th'e invention is larity. Electrolyte-is added until approximately applied Ato a. primary cell having an anode of 1/8 inch above the tops of the rolls -and a measzinc or itsv equivalent, an alkaline electrolyte and v aired quantity of mercury I3 is introduced on a, depolarizing electrode formed of an oxidizing top of the rolls `in contact with the zinc. The agent, for example mercurio oxide or cupric oxide. amount o f mercury used will depend on the area The invention is particularly well adapted for of the zinc and is determined by calculation or the cell compositions described in Samuel Ruben experiment.v Preferably about 1/3 of the mercury applicati-on Serial No. 486,367, flled May 10 1943. is placed at the center and 2A; near the outer Referring to the drawing, Figure 1 shows a edge. The dish is then covered and placed in method for making a composite anode strucan oven at 60 C. for several hours, for example ture 9 comprising a corrugated strip of zinc foil 12-16 hours. -This permits the mercury to spread I0 and a strip of absorbent paper Il. Corrugated 30 over the entire zinc foil surface and completely zinc is preferred to allow for paper expansion amalgamate it. In general, the heating operabut plain zinc ribbon may be used if desired. The tion involves holding the foil assembly at a temzinc strip is narrower than the paper and the perature above 50 C. for several hours. With CWO are WOllnd t0gether as shown in offset relathe preferred electrolyte described in the Samuel y tion to provide a projecting zinc portion at one Ruben application, cells may be held in th'e elecen-:l of the roll and paper at the other end. The trolyte in this condition for several days, if repaper strip is somewhat longer than the zinc to quired, without damage. provide at least one complete turn of paper on Just before assembly the excess electrolyte is the inside and outside of the roll. drainedirom the anodes for several minutes un- Zinc of high purity and clean surface should der moderate vacuum. preferably be used to avoid adverse electrolytic The depolarizing electrode I6 comprises an effects so far as possible. oxide composition which is pressed as a com- The paper strip Il should be resistant to alpact layer or pellet into the bottom of an iron kalies. Apaper which has been used successfully or steel cup, I1 to form the cathode-container is formed from a mixture of wood and hemp sub-assembly. Thepbottom and lower inside walls fibres, the paper pulp being treated or washed of the cup are first painted with a graphite suswith an alkali solution, such as sodium hydroxpension 33 which' promotes good electric conide solution, in .the process of paper manufactact. ture. This produces a reaction of the alkali with When ready for assembly the anode-spacer aspa'rt of the paper constituents and results in a 50 sembly is inserted in the cup zinc end up. The

roll is pressed down so that the paper II makes contact with the top surface of the cathode I6.

yA zinc disc I8 having a thick central portion and anarrower rim I9 is placed on top of the zinc end of the roll and a ring or band 20 of synthetic rubber or other plastic insulating sealing material is placed over the rim I9. The free edge 2l of cup l1 -is then spun over the ring 20 toseal the cell and t0 apply pressure between top disc I8 and zinc anode foil I0. It is found that this pressure contact remains perfect for the life of the cell.

As one example of a cell constructed according to the invention a zinc foil strip .002 inch thick, if inch wide and 13 inches long is corrugated with about 50 corrugations per inch. Two layers of porous paper. such as lter paper, are u'sed each .004 inch thick, 12/32 inch wide and 15 inches long. The cup I'l has an inside diameter of V2 inch and a depth of about 1/2 inch exclusive of the ange 2l. Two grams of the preferred depolarizer material consisting of 90% mercurio oxide and micronized graphite is pressed in the bottom of the cup resulting in a layer approximately .090 inch thick. The paper Il, being soft and porous, swells and expands to close the space between turns at the bottom end of the anode roll so that all electrolytic conduction in the cell is through electrolyte held absorbed in the paper.

By way of example, only, one electrolyte of the type described in the Samuel Ruben application which can be used is formed by dissolving '75 grams KOH in 100 ml. of water and boiling with an excess of zinc oxideuntll the electrolyte is saturated therewith, then cooling and vacuum ltering through a ne grain glass filter so that a clear solution is obtained.

Figure i illustrates a modified cell wherein the compact in the bottom of the container includes an inert microporous barrier disc 21 which is pressed on top of the depolarizer 26. Barrier 21 may be a porous ceramic material or other porous material which is inert to the electrolyte. This construction is desirable when the depolarizer consists of cupric oxide or other oxides which have a tendency to migrate to the anode at elevated temperatures. The paper il itself affords substantial protection against migration under normal conditions but the barrier disc improves the protection where extreme temperature conditions or long shelf life are encountered. A suillciently fine barrier may be used to retard migration. effects even where these eiects involve actual solution of a small amount of the depolarlzing oxide.

A modiiled cell top 28 is also illustrated in Figure 4 comprising -a zinc disc having a central depression drawn therein. External contact is made to the zinc terminal disc I8 or 28 by a pressure clip or by a soldered terminal wire as required.

While speciilc embodiments of the invention have been described, itis intended tc cover the invention rbroadly within the spirit and scope of the appended claims.

f What-*is claimed is:

1. The method of making an anode-spacer assembly' for a primary cell which comprises rolling together a strip of anode metal foil and porous sheet spacer material in offset relation whereby the foil projects from one end of the roll, impregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact-with the projecting edge-of said foil, and maintaining said contact until mercury has spread over-th`e entire foil surface.

2. The method of making an anode-spacer sub-assembly for a primary Acell which comprises rolling together a strip of zinc foil and porous sheet spacer material in oiset relation whereby the foil projects from one end of the roll, impregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact with the projecting edge of said foil, and maintaining said contact until mercury has spread over the entire foil surface.

3. The method of making an anode-spacer assembly for, a primary cell which comprises rolling together a strip of anode metal foil and porous sheet spacer material in offset relation whereby the foil projects from one end'of the roll, lmpregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact with the projecting edge of said foil, and holding the assembly at an elevated temperature until amalgamation is substantially complete.

4. The method of making an anode-spacer astogether a strip of anode metal foil and porous sheet spacer material in oilset relation whereby the foil projects from one end-of the roll, impregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact with the projecting edge of said foil, and holding the assembly at an elevated temperature for an extended period of time to promote spreading of the mercury over the foil surface. l

5. The method of making an anode-spacer subassembly for a primary cell which comprises rolling together a strip of zinc foil and porous sheet spacer material in offset relation whereby the foil projects from one end of the roll, impregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact with the projecting edge of said foil, and holding the assembly at a temperature above 50 C. for several hours.

6. The method of making an anode-spacer subassembly for a primary cell which comprises rolling together a strip of zinc foil and porous sheet spacer material in offset relation whereby the foil projects from one end of the roll, impregnating the roll with electrolyte and then amalgamating said foil by bringing mercury into contact with the projecting edge of said foil, and holding the assembly at a temperature in the order of 60 C. fork several hours.

7. The method of amalgamating an electrode metal which comprises immersing the metal in an alkaline solution, bringing' mercury into con-l tact with said metal at limited portions of its area only and holding the electrode in contact with said mercury in said solution at an elevated temperature for an extended period of time to permit said mercury to spread over the surface of said metal and amalgamate therewith.

8. The method of amalgamating a metal foil strip which comprises windingvsaid strip into a roll with an interposed layer of absorbent material impregnating said roll with an alkaline solution and placing mercury in contact with an end of said roll and maintaining said contact for a period sufficient to permit -said mercury to spread over said foil surface and amalgamate therewith.

9. The method of making an amalgamated zinc Y foil electrode assembly for a primary cell which comprises winding a strip of zinc foil into a roll with an interposed-strip of absorbent sheet mate'- rial, impregnati'rigthe assembly with the primary cell electrolyte, placing mercury in contact with the zinc foil at van end of the impregnated roll, holding the assembly thus produced at an elevated temperature for a period at least suillcient to permit spreading of said mercury over substantially all of the surface of said zinc foil.

10. The methodof making a composite electrode for, alkaline primary cells which comprises treating paper pulp with an alkali solution and then making paper from said pulp, interwinding strips of said paper and of electrode foil into a roll, and impregnating said roll with an alkaline primary cell electrolyte, and then placing mercury in contact with the foil at an end of said roll and holding the roll and mercury in contact at an elevated temperature to promote spreading of the mercury over the entire surface of the foil.

1l. The method of making a composite electrode -for alkaline primary cells which comprises treating'paper pulp with an alkali solution and then making paper from said pulp, interwinding strips of said paper and of zinc foil into a roll, and impregnating said roll with an alkaline primary cell electrolyte, and then placing mercury in contact with the foil at an end oisaid roll and holding the roll and mercury in contact at an elevated temperature to promote spreading of REFERENCES CITED The following references are of record in the file of this patent:

UNTTED STATES PATENTS v OTHER REFERENCES Viaal et al., Circular of Bureau of Standards. N0. 79 (1923), Pages 22, 23. 

